Recent automotive engine technology in the areas of exhaust emission reduction and fuel economy has moved toward the recirculation of a portion of the exhaust gases of an internal combustion engine through the intake manifold thereof and higher heating of the air and fuel misture being supplied to the intake manifold. However, many vehicles equipped with internal combustion engines manufactured more than one or two years ago do not include provisions for recirculation of exhaust gases and higher heating of the air and fuel mixture supplied to the corresponding intake manifolds. Accordingly, a need exists for an air and fuel mixture heater which may be utilized to retrofit older vehicle engines in order to enable them to enjoy less exhaust emissions and greater fuel economy.